A versatile cation-exchange procedure of measuring the seven major forms of vitamin B6 in biological samples.

A cation-exchange procedure for detecting nanogram quantities of all seven common vitamin B6 metabolites in a variety of biological samples is presented. The procedure uses gradient elution with a single column to effect separation of the seven compounds within 40 to 60 min, depending on the complexity of the sample. Postcolumn addition of buffer and bisulfite ion permits sensitive fluorometric detection of all B6 compounds at the same wavelengths (330 nm activation, 400 nm emission).